Author Topic: What tire to correct speedometer inaccuracy?  (Read 394 times)

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Offline VABird

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What tire to correct speedometer inaccuracy?
on: July 20, 2021, 03:36:11 PM
Having read through many (old) threads regarding speedo inaccuracy. it appears that most if not all of our TEXs read about 5-6% high as compared to a GPS.
The only bike I've had that was any better was my 955i, which was within 1-2% and that's certainly acceptable.
On my T-bird, I found that going to a different rear tire got the speedo much more accurate, but put the odometer off accordingly reading low.
SO... the question in the title. Has anyone found a tire size that corrects, at least partially, the error? I'm getting ready to replace the tires and would like to get one that solves this issue, which I admit is a minor one, yet irritating nevertheless.

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Offline Hawk281

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Re: What tire to correct speedometer inaccuracy?
Reply #1 on: July 20, 2021, 03:52:30 PM
Mine has been four miles an hour fast, no matter what tire. I just auto figure that in when I look at the speedo. Unfortunately it makes me do the same thing with my other vehicles, which means I’m exceeding the speed limit all the time. :745:

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Offline CraptainC

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Re: What tire to correct speedometer inaccuracy?
Reply #2 on: July 20, 2021, 05:34:19 PM
What's a speedo  :187:

Interestingly GPS calculates the speed in straight lines (so not so accurate on the twisty's) and relies on good satellite reception.... So if you plan to use it for calibrating that thing next the rev counter, do it on a straight road with a good open sky 
 :821:
CC

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Offline VABird

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Re: What tire to correct speedometer inaccuracy?
Reply #3 on: July 20, 2021, 05:46:07 PM
*Originally Posted by CraptainC [+]
What's a speedo  :187:

Interestingly GPS calculates the speed in straight lines (so not so accurate on the twisty's) and relies on good satellite reception.... So if you plan to use it for calibrating that thing next the rev counter, do it on a straight road with a good open sky 
 :821:
CC

Really? Speedo(meter)
That is how it's being done. It's off 3 MPH at 50.

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Offline Hawk281

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Re: What tire to correct speedometer inaccuracy?
Reply #4 on: July 20, 2021, 06:21:43 PM
Speedo? I guess I’m just advertising my age.

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Offline CraptainC

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Re: What tire to correct speedometer inaccuracy?
Reply #5 on: July 20, 2021, 06:36:23 PM
*Originally Posted by VABird [+]
Really? Speedo(meter)

Just joking - I know exactly what a speed is  .....  just don't generally use mine much  :007:

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Offline VABird

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Re: What tire to correct speedometer inaccuracy?
Reply #6 on: July 20, 2021, 06:38:10 PM
 Somehow, I just knew that "speedo" thing would come out!
Last Edit: July 20, 2021, 06:43:32 PM by VABird

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Offline Chippy4467

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Re: What tire to correct speedometer inaccuracy?
Reply #7 on: July 20, 2021, 08:40:33 PM
Somehow, I just knew that "speedo" thing would come out!
probably an image we didn't need  :005:

I put a set of Continental Trail Attack 3 's on earlier this year and found the speedo matched the GPS more closely than it had on PR4 trails.  But now the are wearing its not so good. 

Most speedos read high because A. they are not allowed to read low by law in many countries, and B. (being cynical) it make more money for manufacturer - services and spares requirements come around sooner - small margins maybe but it sure makes a difference

Suggest you just ride it  :001:
Chippy

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No trees were killed in the sending of this message, but a large number of electrons were terribly inconvenienced.......

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Offline VABird

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Re: What tire to correct speedometer inaccuracy?
Reply #8 on: July 20, 2021, 09:22:19 PM
*Originally Posted by Chippy4467 [+]
....
Most speedos read high because A. ...... and B. (being cynical) it make more money for manufacturer - services and spares requirements come around sooner - small margins maybe but it sure makes a difference

Agree with "A", but not "B" because the odometers seem to be spot on.
I'm really looking for the tire size , preferably for an all road tire. This bike is too heavy for me to consider  riding other than road and possibly compacted gravel. And, I've had enough of the noise & vibration of the 80/20 tires on my 955i.
Last Edit: July 20, 2021, 09:35:12 PM by VABird

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Offline VABird

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Re: What tire to correct speedometer inaccuracy?
Reply #9 on: July 20, 2021, 10:35:11 PM
All the previous may be a moot point.
I found a tire circumference calculator:   https://tiresize.com/speedometer-calibration/
In order to get a happy medium of speedo(meter) and odo(meter) inaccuracies (+-2-3%), the ideal tire size would be 180/50 R17, which nobody seems to make!
If it wasn't for the pic of CraptainC in his speedo.....
Last Edit: July 20, 2021, 10:38:12 PM by VABird